1. Field of the Invention
The invention relates to frame relay communications, and more particularly to a method and apparatus for identifying on which channel a frame relay communication is made.
2. Discussion of the Related Art
Computer networks are widely used to provide increased computing power, sharing of resources and communication between users. One type of network is referred to as a frame relay network--it complies with an interface standard that provides statistical time division multiplexing and circuit switching, and is typically optimized for the transport of protocol-oriented data.
In a typical frame relay network, a communications carrier provides a designated data throughput between two particular entry points (sites) to the network. The data is passed through a "connection," which is also referred to as a "virtual circuit." A permanent virtual circuit (PVC) has one guaranteed data throughput, while a switched virtual circuit (SVC) allows additional throughput in response to a specific demand. Each connection (i.e., virtual circuit) is identified by a data link connection identifier or index (DLCI) number. Many DLCI numbers have local significance only, i.e., a connection identified by a first DLCI number at a first site, may be identified by a different DLCI number at a second site. The connection may be implemented via a set data path, or the data may be re-routed through a different data path depending upon circuit performance. Additional detail on frame relay architectures, protocols, and analysis is described in Analyzing Broadband Networks, Mark A. Miller, M&T Books, pp. 31-169 (1994), which is hereby incorporated by reference.
In the operation and maintenance of computer networks, a number of issues arise including traffic overload on various parts of the network, optimum placement and interconnection of network resources, security, isolation of network faults, and the like. These issues become increasingly complex and difficult to understand and manage as the network becomes larger and more complex. For example, if a network device is not sending messages, it may be difficult to determine whether the fault is with the device itself, a data communication link, or an intermediate network device between the sending and receiving devices.
Network management systems have been developed to resolve such issues. Older systems typically operated by collecting large volumes of information, which then required evaluation by a network administrator; this placed a tremendous burden on, and required a highly-skilled network administrator. Newer network management platforms systematize the knowledge of the networking expert such that common problems can be detected, isolated and repaired, either automatically or with the involvement of less-skilled personnel. Such a system typically includes a graphical representation of that portion of the network being monitored by the system. An example of the newer automated system is the Spectrum.TM. network management platform available from Cabletron Systems, Inc., Rochester, N.H. USA.
It would be desirable to provide a network management system that can determine and display a graphical representation of particular connections which exist in a frame relay network. However, a single interface device, such as a router, switch, or bridge, may have several interfaces, each of which communicates with the frame relay network. Additionally, each interface may communicate over several distinct frame relay connections. Still further, each interface device may not have specific knowledge regarding the other interface device(s) with which it is communicating, much less the specific virtual circuits (connections) that exist at any given time. Accordingly, it would be desirable to be able to determine particular connections from data which is available from the interface devices.